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Details

Details

  • Name

    António Bernardo Ferreira
  • Role

    Researcher
  • Since

    01st November 2011
  • Nationality

    Portugal
  • Contacts

    +351228340554
    antonio.b.ferreira@inesctec.pt
015
Publications

2023

Precipitation-Driven Gamma Radiation Enhancement Over the Atlantic Ocean

Authors
Barbosa, S; Dias, N; Almeida, C; Silva, G; Ferreira, A; Camilo, A; Silva, E;

Publication
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES

Abstract
Gamma radiation over the Atlantic Ocean was measured continuously from January to May 2020 by a NaI(Tl) detector installed on board the Portuguese navy's ship NRP Sagres. Enhancements in the gamma radiation values are identified automatically by an algorithm for detection of anomalies in mean and variance as well as by visual inspection. The anomalies are typically +50% above the background level and relatively rare events (similar to<10% of the days). All the detected anomalies are associated with simultaneous precipitation events, consistent with the wet deposition of scavenged radionuclides. The enhancements are detected in the open ocean even at large distances (+500 km) from the nearest coastline. Back trajectories reveal that half of these events are associated with air masses experiencing continental land influences, but the other half do not display evidence of recent land contact. The enhancements in gamma radiation very far from land and with no evidence of continental fetch from back trajectories are difficult to explain as resulting only from radionuclides with a terrestrial source such as radon and its progeny. Further investigation and additional measurements are needed to improve understanding on the sources of ambient radioactivity in the open ocean and assess whether gamma radiation in the marine environment is influenced not only by radionuclides of terrestrial origin, but also cosmogenic radionuclides, like Beryllium-7, formed in the upper atmosphere but with the ability to be transported downward and serve as a tracer of the aerosols to which it attaches. Plain Language Summary Radioactive elements such as the noble gas radon and those produced by its radioactive decay are naturally present in the environment and used as tracers of atmospheric transport and composition. In particular, the noble gas radon, being inert and of predominantly terrestrial origin, is used to identify pristine marine air masses with no land contamination. Precipitation over land typically brings radon from the atmosphere to the surface, enhancing gamma radiation on the ground, but such enhancements have not been identified before nor expected over the ocean due to the low amount of radon typical of marine air masses. Here we report, for the first time, gamma radiation enhancements associated with precipitation in the oceanic environment, using measurements performed over the Atlantic Ocean in a campaign onboard the Portuguese navy ship NRP Sagres.

2023

TURTLE Robotic Lander in the context of REP2022 military exercise

Authors
Martins, A; Almeida, J; Almeida, C; Matias, B; Ferreira, A; Machado, D; Ferreira, H; Pereira, R; Soares, E; Peixoto, PA; Silva, E;

Publication
OCEANS 2023 - LIMERICK

Abstract
This paper presents the TURTLE hybrid robotic lander in the context of the field trials performed in the REP(MUS) 2022 military exercise. The TURTLE robot combines the characteristics and mobility of an autonomous underwater vehicle with the ones of a seabed lander, having been designed for extended permanence on the sea bottom and efficient ascending and dive to the deep sea. The REP( MUS) 2022 exercises organized by the Portuguese navy in collaboration with NATO organizations and other institutions demonstrated the large-scale use of unmanned marine systems in an operational scenario. The robotic system is presented as well as some of the results and experience from the field trials.

2023

Methodological insights from unmanned system technologies in a rock quarry environment and geomining heritage site: coupling LiDAR-based mapping and GIS geovisualisation techniques

Authors
Pires, A; Dias, A; Silva, P; Ferreira, A; Rodrigues, P; Santos, T; Oliveira, A; Freitas, L; Martins, A; Almeida, J; Silva, E; Chaminé, HI;

Publication
Arabian Journal of Geosciences

Abstract

2022

3DupIC: An Underwater Scan Matching Method for Three-Dimensional Sonar Registration

Authors
Ferreira, A; Almeida, J; Martins, A; Matos, A; Silva, E;

Publication
SENSORS

Abstract
This work presents a six degrees of freedom probabilistic scan matching method for registration of 3D underwater sonar scans. Unlike previous works, where local submaps are built to overcome measurement sparsity, our solution develops scan matching directly from the raw sonar data. Our method, based on the probabilistic Iterative Correspondence (pIC), takes measurement uncertainty into consideration while developing the registration procedure. A new probabilistic sensor model was developed to compute the uncertainty of each scan measurement individually. Initial displacement guesses are obtained from a probabilistic dead reckoning approach, also detailed in this document. Experiments, based on real data, demonstrate superior robustness and accuracy of our method with respect to the popular ICP algorithm. An improved trajectory is obtained by integration of scan matching updates in the localization data fusion algorithm, resulting in a substantial reduction of the original dead reckoning drift.

2022

An holistic monitoring system for measurement of the atmospheric electric field over the ocean - the SAIL campaign

Authors
Barbosa, S; Dias, N; Almeida, C; Amaral, G; Ferreira, A; Lima, L; Silva, I; Martins, A; Almeida, J; Camilo, M; Silva, E;

Publication
OCEANS 2022

Abstract
The atmospheric electric field is a key characteristic of the Earth system. Despite its relevance, oceanic measurements of the atmospheric electric field are scarce, as typically oceanic measurements tend to be focused on ocean properties rather than on the atmosphere above. This motivated the set-up of an innovative campaign on board the sail ship NRP Sagres focused on the measurement of the atmospheric electric field in the marine boundary layer. This paper describes the monitoring system that was developed to measure the atmospheric electric field during the planned circumnavigation expedition of the sail ship NRP Sagres.